The Web site for this river town advertises "location, location, location" -- 20 minutes from downtown St. Louis on the National Scenic Byway where the Mississippi River meets the Missouri River.

Nowhere does it mention that the northern half of the village sits atop an estimated 3 million gallons of leaded gasoline that have seeped into the ground since the 1960s on its way from the refinery east of town to the river barges and truck terminals that carry it to Midwest gas stations.

Environmental officials think the gas leaked from about 20 underground pipelines and perhaps from the refinery itself, which has had several owners during the last 64 years.

Because of varying types of soil, the gas is a few feet underground in some spots and far deeper in others. Heavy rains or a rise in the Mississippi River raise the water table, forcing fumes into buildings through cracks in their foundations or into the streets through sewers.

Over the years, at least 26 residential basement fires have been blamed on combustible soil gas. Fumes sometimes ignite into thin blue flames that resemble the pilot light on a stove. Noxious odors leave residents complaining of nausea, headaches and fatigue. North Side homeowners say their property values have tanked.

"Only an idiot would buy it," Noah Greer, 75, said of the house he has lived in since June 1976. "Of course, only an idiot would stay in it."

For decades, state environmental officials have tried unsuccessfully to solve the problem. Now, under the watch of the federal Environmental Protection Agency, a coalition of oil companies called the Hartford Working Group has begun a cleanup that has cost at least $15 million so far and could take as many as 30 years.

The group's efforts -- including sealing basements, adding ventilation systems and extracting gasoline vapors from the ground and sewers -- do not inspire confidence in residents. They are weary of years of failed attempts.

"We're the guinea pigs while they use trial and error," resident Mike Hanbaum said. "The bottom line is that they can't get this gas out of the ground, and we continue to suffer."

More than 130 homeowners have joined a lawsuit filed last year against several oil and pipeline companies that did business in and around Hartford. At least 60 residents have filed individual lawsuits against the companies.

While some residents want to see the 235-plus affected home sites condemned, bulldozed and dredged, oil companies and government agencies say that is not in the plans.

Village leaders resist that idea because Hartford would lose a significant part of its tax base. And federal officials doubt it would hasten the cleanup because there is so much contaminated soil that it is unsafe to move it.

"I don't think there is a landfill in the world big enough to take it," said Chris Cahnovsky, a regional manager for the Illinois Environmental Protection Agency. "You're talking about a couple hundred thousand truckloads of dirt."

Federal officials predict the latest efforts by the oil companies will relieve much of the odor problem.

"The residents will soon see that things will be better," said Kevin Turner, an environmental scientist at the federal EPA.

When the problems surfaced in the 1960s, Hartford officials attributed them to swamp gas.

Then basements caught fire. State officials determined that thousands of gallons of gas were leaving the refinery and not making it through pipelines to the terminals. Fuel vapors, igniting flames beneath Hartford, meant the system was springing perilous leaks.

"I looked down the stairs, and there were flames coming from every crack," said Virden Dobey, 71, recalling one fire in his basement in the 1970s. "It was like they turned the stove on."

Years of complaints brought little relief. Refinery owners dug three wells in the 1970s and began pumping liquid fuel from the ground. The process worked slowly and was limited to areas where the wells were dug. Many parts of north Hartford still were sitting above gasoline.

Then in the 1990s, the odors worsened. On state orders, the oil refinery installed a system to suck vapors from the ground and burn them off.

But after more than a decade, the system began breaking down. After several weeks of steady downpours during a wet spring in 2002, northern Hartford was again besieged by such strong gas smells and dangerous vapors that residents were forced to evacuate.

"The odor would knock you over," said Dave Phillips, who added that he thought the problems had been solved when he moved into his house in March 1998.

Finally, in 2003, the federal EPA stepped in, joining state and county officials in legal and enforcement actions against oil and pipeline companies that worked in and around Hartford. A consortium of current and former oil companies negotiated with the federal EPA to underwrite and coordinate an emergency cleanup.

Much of northern Hartford now is a construction zone. Crews have dug below streets and into sewer systems to pull vapors from the ground and transport them to treatment units for burning.

In more than 100 basements, workers have sealed cracks, installed ventilation systems and provided meters to monitor vapor levels. And this month, the Hartford working group began using portable wells to move about the village and again suck gas from the ground.

Still, federal EPA officials said it may take at least 20, and likely 30 years, before the gas is fully eliminated from Hartford.

Although some residents say the oil companies' efforts are working, others are skeptical. At least 40 homeowners have refused the working group's help. Some worry that cooperation might hinder their legal standing.

"People have been lying to us for years," said Bob May, who installed his own makeshift vent years ago after fires in his house and now is a party to a suit. "Why should we trust them now?"